DTIC ADA360425: Forest Response to High Duration and Intensity Flooding along Pool 26 of the Upper Mississippi River

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by  Defense Technical Information Center

Project Status
Report 99-01
Upper Mississippi River
Long Term Resource Monitoring Program
U.S. Geological Survey
Forest Response to High Duration and Intensity Flooding
along Pool 26 of the Upper Mississippi River
by
Robert J. Cosgriff, John C. Nelson and Yao Yin
Many natural resource managers could not anticipate The effect of flooding on floodplain forests is not homogeneous and is
the effects that the flood of 1993 would have on floodplain largely dependent upon flood frequency, duration, intensity, timing,
forests of the Upper Mississippi River. Previous experience and stage of successional development. Most floodplain trees are
suggested that floodplain forests were adapted to such events adapted to survive moderate floods, however, tree species are consid-
and should only experience removal of upland aid non-na- ered susceptible to high duration and intensity flooding events, espe-
tive species. However, when trees considered highly flood cially when these events occur during the growing season. Questions
tolerant did not leaf out in the spring of 1994, natural re- regarding forest community response following high duration and in- CO
source managers began to realize the serious impact that a tensity events have arisen.
CD
large-scale flood could have on floodplain forest communi-
The flood of 1993 provided an opportunity to document flood-
ties. To better understand these impacts, researchers with
plain forest response to a high intensity, long duration (195 days) flood CO
the Long Term Resource Monitoring Program at Pool 26 of
that occurred during the growing season. We quantified the percent o
the Upper Mississippi River System (UMRS) began describ-
ing forest community response to the large-scale flood of (over)
w
1993.
Species Composition
o
The floodplain forests of the UMRS are some of the Tree Species
Mixed Community
most productive ecosystems worldwide. These communi- ■Maple, Box elder, Ash
ties provide habitat and forage for many species of wildlife, □Elm, Hackberry
BlOther
produce timber, and provide a valuable carbon dioxide sink.
□Willow, Cottonwood o
Like many other plant communities, floodplain forest suc- Maple Community Oak Community
IpQak
cessional patterns are largely driven by disturbance events
(e.g., fire, wind-throw, flooding, drought, and physical ero-
Forest Mortality
sion/deposition). Black willow and eastern cottonwood re-
generate on recent deposits of substrate (mainly sand) cre-
ated by the river. As a result of annual floods, fine sediment
drops out of suspension and the low landform occupied by
the willow/cottonwood community develops into a low ter-
race. At the same time, the willow/cottonwood community
is gradually being replaced by silver maple and green ash.
The process of terrace building continues and communities
of mixed forests and oak forests develop as elevation increases
and the frequency of flooding decreases. Understanding how
these communities respond to the various disturbance events,
particularly large scale flooding, is important to natural re-
source managers who are trying to manage for specific or
diverse floodplain forest communities. Tree Species
Figure 1. Percent mortality of maple, mixed, and oak forests along
Flooding is the most common disturbance event on a
Pool 26 of the Upper Mississippi River System following the flood of
floodplain, occurring almost annually at lower elevations.
1993.
DTIC QÜALHT IN GEECTKD I
We believe that oak sites may be set back to an earlier
successional stage as silver maple, green ash trees, and
green ash saplings had better survivorship on these
sites. This prediction excludes sites dominated by
overcup oak, because these sites had excellent survi-
vorship (19% mortality) and were relatively unaffected
by the flood disturbance. We could draw no conclu-
sions about the mixed forest community. Even though
swamp privet, hawthorn and persimmon had the best
survivorship on these sites, they are considered un-
derscory trees and are generally not considered forest
dominants. Although the maple sites suffered moder-
ate mortality (example, Figure 2) in the dominant trees
(42% for silver maple and 21% for green ash), there
are a large number of dominant trees remaining and
we believe that these sites will regenerate back to
maple communities.
Figure 2. Maple/ash forest community, Pool 26 of the Upper Mississippi
River System, Spring 1995. This photograph is available in color through the The high mortality of hard- and softmast produc-
UMESC Home Page at http://www.umesc.usgs.gov/ ing species (e.g., pin oak and hackberry) across all for-
est communities will create problems for natural re-
mortality of three floodplain forest community types (maple, mixed, and
source managers who are trying to promote wildlife,
oak) along Pool 26 near St. Louis, Missouri. Our results (Figure 1) indicate
particularly game animals. Much of the floodplain for-
there was a community, species and size specific response to the flood event.
ests of Pool 26 are currently managed for waterfowl,
Oak and maple communities responded similarly with an overall tree turkey and whitetail deer. These species rely heavily
mortality of 42% and 41%, respectively. Mixed communities exhibited a upon acorn production for forage during the fall and
higher mortality (60%). Among all communities, the most negatively im- winter. The loss of pin oaks and oak forests in general
pacted tree species were hackberry (ranging from 74% to 100%) and pin may have a corresponding decrease in the ability of
oak (ranging from 54% to 80%). Saplings suffered a higher mortality rate floodplain forests to support important game species
than trees. Maple and mixed communities lost 80% of the saplings, while as well as other wildlife.
oak communities lost 56% of the saplings. All saplings seemed equally sus-
We are currently trying to further predict forest
ceptible, however, common persimmon, swamp privet and green ash had
successional trends using seedling regeneration data
better survivorship than most (average mortality of 36%, 57% and 48%,
related to overstory canopy removal, location in re-
respectively).
gards to seed trees, soil properties, and herbaceous
Estimating forest successional patterns following any disturbance event cover. We ultimately hope to resample the forest sites
is often difficult. To accurately predict community trend, sampling at more on Pool 26 and use the information in a model to bet-
than one point in time is required. By examining the tree and sapling survi- ter predict forest community trends following cata-
vorship results, we can only suggest how forest communities might respond. strophic flood events. □
For further information, contact
Robert J. Cosgriff John C. Nelson Yao Yin
Illinois Natural History Survey Illinois Natural History Survey U.S. Geological Survey
LTRMP Field Station LTRMP Field Station Upper Midwest Environmental Sciences Center
4134 Alby Street 4134 Alby Street 2630 Fanta Reed Road
Alton, Illinois 62002 Alton, Illinois 62002 La Crosse, Wisconsin 54603
Phone: [phone] Phone: [phone] Phone: [phone], ext.53
Fax: [phone] Fax: [phone]
E-mail: [email protected]
Email: [email protected] Email: [email protected]
Project Status Reports (PSRs) are preliminary' Long Term Resource Monitoring Program documents whose purpose is to provide information on Program activi-
ties. Because PSRs are only subject to internal peer review, they may not be cited. Use of trade names does not imply U.S. Government endorsement of commercial
products. All LTRMP Project Status Reports are accessible through the Upper Midwest Environmental Sciences Center's Home Page at http://www.umesc.usgs.gov/
January 1999 PSR "-°1
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